The proposed research seeks to establish the relationship between the neuropeptide oxytocin (OT) and social behaviors in older adults. The goal is to establish a causal relationship between OT release and the desire for, and participation in, social activities. Because social ties are strongly protective of health and life, and yet typically decline in seniors, understanding the neural basis for sociality is an important goal. This application describes two experiments that can substantially increase our understanding of why social behaviors may decline in older adults. Experiment 1 will measure OT release using a recently developed neuroeconomics paradigm in people ranging in age from 15 to 85. This experiment seeks to demonstrate that like other reproductive hormones, OT release declines in middle age and throughout old age. In addition, it will relate OT release to several self-reported social behaviors. This experiment will test if those with greater OT release are more socially active. It will also examine if those who engage in more social activities are subjectively happier in order to provide a possible explanation for the correlation between positive affect and health outcomes. This is particularly important in older adults who are at risk of depression and have an associated poor prognosis if they are depressed. Experiment 2 is the treatment arm of the proposed research. It seeks to establish a causal relationship between OT and social behaviors in older adults by giving co-residential participants a short course of intranasal OT and tracking their motivation for, and engagement in, social activities. Recent research has shown that OT producing neurons are intact in old age, and OT receptors are likely intact as well. If OT is shown to affect social behaviors in older adults then this research will have identified a novel mechanism to "jump-start" the desire to socialize. Experiment 2 is designed to measure the effects during and beyond the treatment period to see if OT infusion produces a longer-term impact on social behaviors. PUBLIC HEALTH RELEVANCE: The proposed research will examine, through a set of experiments, whether a hormone called oxytocin may help explain why social behaviors decline in older adults. It proposes to both measure oxytocin release over the lifespan and to track social behaviors as well as treat older adults for a brief period with synthetic oxytocin. This research has societal value because maintaining social ties is protective for health and life.